The Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.


Math Forum » Discussions » Inactive » Historia-Matematica

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: [HM] Bombelli: Cube root of Complex Nos.
Replies: 8   Last Post: Feb 19, 2001 5:31 AM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Bonnie Shulman

Posts: 20
Registered: 12/3/04
Re: [HM] Bombelli: Cube root of Complex Nos.
Posted: Feb 14, 2001 1:53 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Oops, so sorry! cos(arctan 11/2) would not be hard to find.
What I meant to write was cos[(arctan 11/2)/3]. And, indeed,
as one quickly realizes, this leads to the angle-tripling formula
(4 cos^3 x - 3 cos x = cos 3x). And, indeed, circularly, one
basically ends up with one's original cubic!


--Bonnie Shulman






Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© The Math Forum at NCTM 1994-2018. All Rights Reserved.